#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <unistd.h>

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <event.h>
#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/util.h>

int tcp_connect_server(const char* server_ip, int port);

void cmd_msg_cb(int fd, short events, void* arg);
void server_msg_cb(struct bufferevent* becv, void* arg);
void event_cb(struct bufferevent* bev, short event, void* arg);

int main(int argc, char** argv) {
	if (argc < 3) {
		printf("please input 2 parameter\n");
		return -1;
	}

	// 两个参数依次是服务器端的IP地址、端口号
	int sockfd = tcp_connect_server(argv[1], atoi(argv[2]));
	if (sockfd == -1) {
		perror("tcp_connect error");
		return -1;
	}

	printf("connect to server succ\n");

	struct event_base* base = event_base_new();

	struct bufferevent* bev = bufferevent_socket_new(base, sockfd, BEV_OPT_CLOSE_ON_FREE);

	// 监听终端输入事件
	struct event* ev_cmd = event_new(base, STDIN_FILENO, EV_READ | EV_PERSIST, cmd_msg_cb, (void*)bev);

	event_add(ev_cmd, NULL);

	// 当socket关闭时会用到回调参数
	bufferevent_setcb(bev, server_msg_cb, NULL, event_cb, (void*)ev_cmd);
	bufferevent_enable(bev, EV_READ | EV_PERSIST);

	event_base_dispatch(base);

	printf("finished\n");
	return 0;
}

void cmd_msg_cb(int fd, short events, void* arg) {
	char msg[1024] = {0};

	int ret = read(fd, msg, sizeof(msg));
	if (ret < 0) {
		perror("read fail");
		exit(1);
	}

	struct bufferevent* bev = (struct bufferevent*)arg;

	// 把终端的消息发送给服务器端
	bufferevent_write(bev, msg, ret);
}

void server_msg_cb(struct bufferevent* bev, void* arg) {
	char msg[1024] = {0};

	size_t len = bufferevent_read(bev, msg, sizeof(msg));
	msg[len] = '\0';

	printf("recv %s from server\n", msg);
}

void event_cb(struct bufferevent* bev, short event, void* arg) {
	if (event & BEV_EVENT_EOF) {
		printf("connection closed\n");
	} else if (event & BEV_EVENT_ERROR) {
		printf("some other error\n");
	}

	// 这将自动close套接字和free读写缓冲区
	bufferevent_free(bev);

	struct event* ev = (struct event*)arg;

	// 因为socket已经没有, 所以这个event也没有存在的必要了
	event_free(ev);
}

typedef struct sockaddr SA;
int tcp_connect_server(const char* server_ip, int port) {
	int sockfd, status, save_errno;
	struct sockaddr_in server_addr;

	memset(&server_addr, 0, sizeof(server_addr));

	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(port);
	status = inet_aton(server_ip, &server_addr.sin_addr);

	if (status == 0) { // the server_ip is not valid value
		errno = EINVAL;
		return -1;
	}

	sockfd = ::socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd == -1) {
		return sockfd;
	}

	status = ::connect(sockfd, (SA*)&server_addr, sizeof(server_addr));
	if (status == -1) {
		save_errno = errno;
		::close(sockfd);
		errno = save_errno; // the close may be error
		return -1;
	}

	evutil_make_socket_nonblocking(sockfd);

	return sockfd;
}

